JPH09329329A - Method and device for detecting breakage of combustion instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop a combustion instrument immediately and permit the detection of abnormality if necessary by a method wherein unburnt combustion gas, generated upon starting or stopping the combustion instrument, is detected by a gas sensor whereby the breakage of the combustion instrument is detected. SOLUTION: When breakage, such as cracks, hole opening or the like, is generated on a combustion chamber 1 or a heat exchanger 3 and unburnt fuel gas is leaked out of the broken part toward a protection case 4 upon starting and stopping a gas hot-water supplier, a semiconductor type gas sensor 5 is contacted with the unburnt fuel gas and the electric resistance value thereof is changed. When the change of the electric resistance value has exceeded a preset value, a circuit 8 is operated and a solenoid valve 6 is closed. In this case, when the solenoid valve 6 is opened and the fuel gas is supplied upon starting, the supply of the fuel gas to a gas burner 2 is stopped and an alarm lamp 7 is flashed. On the other hand, when the solenoid valve 6 is closed and the supply of fuel gas is stopped upon stopping, the closed condition of the solenoid valve 6 is maintained and the alarm lamp 7 is flashed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting damages such as cracks and perforations in a heat exchanger of a combustion equipment such as a gas water heater, a fan heater, etc. or a combustion chamber with a gas sensor, and a method for detecting the same. The present invention relates to the detection device used.

[0002]

2. Description of the Related Art In combustion equipment such as gas water heaters and fan heaters, heat exchangers and combustion chambers are cracked and perforated due to thermal fatigue and corrosion due to repeated cold and heat.
High-temperature flame and combustion gas may leak from the damaged part, which may cause a fire accident, which is dangerous. As a measure against such a problem, for example, in Japanese Unexamined Patent Publication No. 5-39921, a temperature detecting means and a humidity detecting means are attached to a combustion device to detect a temperature increase due to a flame and a humidity increase due to moisture in a combustion gas. Then, a method of displaying the abnormality is proposed.

[0003]

However, in the case of the method for detecting the humidity in the combustion gas, there is a fear of malfunction due to changes in the weather (changes in temperature and humidity). Further, in the case of the method of detecting the temperature rise, it is difficult to detect the damage at the very initial stage. That is, when a slight crack occurs in the heat exchanger or the combustion chamber and only a very small amount of flame or combustion gas leaks from the damaged portion, it is difficult to detect this. Furthermore, in the case of the method of detecting a temperature rise, in order to have sufficient detection performance, a plurality of temperature sensors or temperature fuses are scattered around the heat exchanger or the combustion chamber, or a long linear temperature fuse is used. Must be evenly wound around the heat exchanger and the combustion chamber, but in this case, the number of parts increases and the workability of the mounting work also decreases, so the manufacturing cost of the combustion equipment increases.

The present invention has been made on the basis of such a point, and it is possible to reliably detect damage such as cracks and perforations that have occurred in the heat exchanger of the combustion equipment and the combustion chamber to prevent the occurrence of a fire accident or the like. Combustion equipment damage detection method that can be prevented in advance,
It is an object of the present invention to provide a damage detection device using this detection method.

[0005]

In order to achieve the above-mentioned object, the present inventor has proposed a method for detecting damages occurring in a heat exchanger or a combustion chamber of a combustion device with a gas sensor, the type of combustion gas, the gas sensor As a result of earnest studies taking into consideration the type and output value of the gas sensor, the combustion gas generated when starting or stopping the combustion equipment contains a large amount of unburned fuel gas. It has been found that all the conventionally known gas sensors have a high output for the fuel gas for combustion. The present inventor has completed the present invention based on this finding.

That is, the method for detecting damage to a combustion device according to the present invention is characterized in that the damage to the combustion device is detected by detecting an unburned fuel gas generated when the combustion device is started or stopped. It is a thing. At this time, it is possible to use a semiconductor gas sensor as the gas sensor.

Further, a damage detection device for combustion equipment according to the present invention is a detection equipment using the above-mentioned detection method. The detection equipment comprises a gas sensor and combustion of the combustion equipment when the gas sensor emits an abnormal signal. Combustion control means for stopping the
Also, it is characterized in that it is composed of an alarm generating means for notifying an abnormality as necessary and a circuit for operating them.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the gas sensor, it is possible to use various conventionally known gas sensors such as a semiconductor type gas sensor, a catalytic combustion type gas sensor, and a solid electrolyte type gas sensor. However, the semiconductor is inexpensive and easy to maintain. It is preferable to use a gas sensor.

As the semiconductor type gas sensor, tin oxide,
Known are gas-sensitizers containing metal oxide semiconductors such as indium oxide and tungsten oxide as main components and metal catalysts such as gold, platinum, palladium and ruthenium (catalyst-sensitized semiconductor gas sensor). Therefore, among them, one having a configuration showing a high output with respect to the fuel gas used in the combustion equipment is appropriately selected. For example,
Combustion devices that use city gas as the fuel gas should have hydrogen gas output, and combustion devices that use LPG or kerosene as the fuel gas should have high output power to hydrocarbon gas. Just select it. As an example of a gas sensor showing a high output with respect to hydrogen gas, for example, JP-A-3-259736 and JP-A-6-148 are known.
For example, those disclosed in Japanese Patent Publication No. 112 are listed.

The installation location of the gas sensor may be appropriately selected in consideration of the structure of the combustion equipment and the like, and is not particularly limited. When the combustion equipment is a gas water heater, for example,
It may be installed on the inner wall of a protective case surrounding the heat exchanger and the combustion chamber. When the combustion device is a fan heater, etc., the inner wall of the protective case surrounding the combustion chamber,
It may be installed in the warm air introduction route to the room.
No matter where the gas sensor is installed,
The gas leaking from the heat exchanger and the combustion chamber diffuses in a wide range, and thus the gas sensor can reliably detect this. Therefore, it is not necessary to disperse a plurality of detecting means (temperature detecting means such as temperature fuses) unlike the conventional case.

The combustion control means is, for example, a solenoid valve which controls the combustion by stopping the supply of the fuel to the combustion equipment when the gas sensor of the above construction makes contact with the unburned fuel gas and gives an abnormal signal. That is. The alarm generating means is an alarm lamp, an alarm buzzer, or the like for notifying an abnormality by light or sound when the gas sensor having the above-mentioned configuration comes into contact with unburned fuel gas and issues an abnormality signal. . The circuit is
It is a circuit for controlling the operation of the gas sensor, the combustion control means, and the alarm generation means.

The damage detection method and the damage detection device of the present invention can be applied to various combustion equipment including a heat exchanger and a combustion chamber, such as a gas water heater, a fan heater, and the like. There are various types of heat exchangers such as a heat pipe type, a two-layer pipe type, and a laminated type, and the present invention can be applied to any of them.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a gas water heater will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a gas water heater incorporating a damage detection device according to the present invention. In FIG. 1, reference numeral 1 is a combustion chamber of a gas water heater, a gas burner 2 is at a lower portion, and a heat exchanger 3 is at an upper portion.
It has. Reference numeral 4 is a protective case surrounding these, and the semiconductor gas sensor 5 is installed on the inner wall thereof. Reference numeral 6 is an electromagnetic valve (combustion control means) that controls the supply of fuel gas to the gas burner 2, reference numeral 7 is an alarm lamp (alarm generation means) that blinks a lamp when an abnormality occurs, and reference numeral 8
Is a semiconductor gas sensor 5, a solenoid valve 6 and an alarm lamp 7.
Is a circuit for controlling the operation of the.

At the time of starting the gas water heater (when igniting), the solenoid valve 6 is opened and the supply of fuel gas to the gas burner 2 is started. At this time, the concentration of unburned fuel gas contained in the combustion gas increases. Should the combustion chamber 1 or the heat exchanger 3 be damaged, such as cracked or punctured, and unburned fuel gas leaks from the damaged portion to the protective case 4 side, the semiconductor gas sensor 5 will cause unburned fuel to flow. The electrical resistance value changes in contact with the gas. At this time, when the change (output) of the electric resistance value of the semiconductor gas sensor 5 exceeds a preset value, the circuit 8 is activated, the solenoid valve 6 is closed, and the supply of fuel gas to the gas burner 2 is stopped. At the same time, the alarm lamp 7 blinks to notify the abnormality.

When the gas water heater is stopped (when the fire is extinguished), the solenoid valve 6 is closed and the supply of fuel gas to the gas burner 2 is stopped. At this time, the concentration of unburned fuel gas contained in the combustion gas increases. Should the combustion chamber 1 or the heat exchanger 3 be damaged, such as cracked or punctured, and unburned fuel gas leaks from the damaged portion to the protective case 4 side, the semiconductor gas sensor 5 will cause unburned fuel to flow. The electrical resistance value changes in contact with the gas. At this time, when the change (output) of the electric resistance value of the semiconductor gas sensor 5 exceeds a preset value, the circuit 8 operates and the alarm lamp 7 blinks while the closed state of the solenoid valve 6 is maintained. To report an abnormality.

FIG. 2 is a graph showing changes in the electric resistance value of the semiconductor gas sensor 5 when the gas water heater is operated with the hole having a diameter of 5 mm opened in the combustion chamber 1. In this embodiment, as the semiconductor gas sensor 5, a thin film semiconductor gas sensor provided with a gas sensitive material containing tin oxide as a main component was used. Also, LPG was used as the fuel gas.

As is apparent from this graph, when the gas burner 2 is burned, the semiconductor gas sensor 5 is immediately connected.
The electric resistance value of was decreased from 150 kΩ to 100 kΩ. When the combustion of the gas burner 2 was stopped after 5 minutes, the electric resistance value decreased from 140 kΩ to 100 kΩ again. That is, although the semiconductor gas sensor 5 used in this embodiment shows almost no output to the combustion gas (carbon dioxide gas) generated when the gas water heater operates, it does not generate when the gas water heater is started or stopped. It can be seen that an extremely high output is exhibited for the unburned fuel gas (hydrocarbon gas) that is burned.

FIG. 3 is a detection circuit diagram for extracting a change in the electric resistance value of the semiconductor gas sensor as an output voltage. In FIG. 3, symbol S is a semiconductor gas sensor, symbol H is a heater, symbol Vc is a circuit voltage, and symbol Vr is a load resistance. The semiconductor gas sensor S and the load resistance Vr are connected in series, and the potential difference across the load resistance Vr is taken out as the output voltage Vout. When the resistance value of the semiconductor gas sensor S is Rs, the output voltage Vout can be expressed by the following equation. Vout = Vc · Vr / (Rs + Vr)

FIG. 4 is a flow chart showing an example of the control operation using the output voltage Vout extracted from the detection circuit shown in FIG. First, when the start button of the combustion device is pressed, the solenoid valve opens and fuel supply is started.
At this time, the output voltage Vout and the set voltage Vs are compared, and when the output voltage Vout is larger than the set voltage Vs, it is determined to be abnormal and the supply of fuel is stopped and an alarm is issued. On the other hand, if the output voltage Vout is equal to or lower than the set voltage Vs, the above comparison is repeated while continuing the fuel supply.

Next, when the stop button of the combustion equipment is pressed, the solenoid valve is closed and the fuel supply is stopped. At this time, the output voltage Vout and the set voltage Vs are compared, and when the output voltage Vout is larger than the set voltage Vs, it is determined to be abnormal and the fuel supply stop state is maintained, and
Generate an alarm. On the other hand, the output voltage Vout is the set voltage V
If s or less, no alarm is generated and the above comparison is repeated.

When the unburned fuel gas leaks from the damaged portion of the combustion chamber of the combustion device or the heat exchanger at the time of starting and stopping the combustion device, the semiconductor gas sensor S
The electrical resistance value Rs of the output voltage Vout significantly decreases, and the output voltage Vout becomes a large value accordingly. Therefore, it is easy to distinguish from the value of the output voltage that fluctuates as the temperature and humidity change, and the abnormality can be determined by the above-mentioned simple and inexpensive circuit without rewriting the set voltage Vs.

[0022]

As described above in detail, according to the present invention, the uncombusted fuel gas contained in the combustion gas generated at the time of starting or stopping the combustion equipment is configured to be detected by the gas sensor. Without being affected by changes in temperature and humidity as in the past, even if a slight damage occurs in any position of the heat exchanger or the combustion chamber, it can be reliably detected and immediately burned in the combustion equipment. Can be stopped and the abnormality can be notified if necessary. Therefore, it is possible to prevent a fire accident from occurring and it is extremely safe. Furthermore, since the number of parts used is small and the work of attaching to the combustion equipment can be performed easily and easily, the manufacturing cost is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention and is a diagram showing a configuration of a gas water heater incorporating a damage detection device.

FIG. 2 is a diagram showing an example of the present invention, and is a graph showing changes in the electrical resistance value of a semiconductor gas sensor.

FIG. 3 is a diagram showing an embodiment of the present invention and is a detection circuit diagram for extracting a change in electric resistance value of a semiconductor gas sensor as an output voltage.

4 is a diagram showing an example of the present invention, and is a flowchart showing an example of a control operation using an output voltage Vout extracted from the detection circuit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Combustion chamber 2 ... Gas burner 3 ... Heat exchanger 4 ... Protective case 5 ... Semiconductor gas sensor 6 ... Electromagnetic valve (combustion control means) 7 ... Alarm lamp (alarm generation means) 8 ... Circuit S ... Semiconductor gas sensor Rs ... Resistance value of gas sensor H ... Heater Vc ... Circuit voltage Vr ... Load resistance Vout ... Output voltage Vs ... Set voltage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01N 27/12 G01N 27/12 A

Claims (3)

[Claims] 1. A method for detecting damage to a combustion device, comprising detecting unburned fuel gas generated at the time of starting or stopping the combustion device with a gas sensor to detect damage to the combustion device. 2. The method for detecting damage to a combustion device according to claim 1, wherein the gas sensor is a semiconductor gas sensor. 3. A detection device using the detection method according to claim 1 or 2, wherein the detection device is a gas sensor and combustion for stopping combustion of a combustion device when the gas sensor issues an abnormal signal. A damage detection device for a combustion device, comprising: a control means, an alarm generation means for notifying an abnormality if necessary, and a circuit for operating these.